1. Field of the Invention
The invention relates to an apparatus for arranging cells on a substrate in a pattern in a culture container, and also to a method for the same.
2. Description of the Related Art
Presently, cells of various animals or plants are cultivated, and new methods for cultivation are now being researched. Techniques of cultivation are utilized for analyzing biochemical phenomena and properties of cells and for generating a new, useful substance. In addition, attempts are now being made to analyze physiological activity or toxicity of artificially made medicines, using cultivated cells.
Particular cells, in particular most animal cells, have a property that they have to attach to something to grow, and hence they cannot live in a long term if they are in a floating condition in vitro. It is necessary to prepare a substrate to which cells attach for incubating such cells having the aforementioned property. In general, a culture dish made of plastic is used as a substrate, and protein (such as collagen and fibronectin) to which cells easily attach is uniformly applied thereto. It is known that the above mentioned protein acts on cells being cultivated to thereby make it easy for cells to attach to the protein and affect a shape of cells.
There has been suggested a technique for attaching cultivated cells only to a small portion of a substrate to thereby arrange cells on a desired region. This technique allows cultivated cells to be applied to an artificial organ, a biosensor and a bioreactor. For arranging cells on a desired region, a method in which a substrate having a plurality of patterns on a surface thereof has been used. Each of the patterns has different adhesive property to cells. Cells are introduced to attach only to the patterns which are processed so that cells are easy to attach thereto, to thereby arrange cells on a particular region in which the cells are to be incubated.
Japanese Unexamined Patent Public Disclosure No. 2-245181 has suggested the use of an electric charge carrying medium on which electrostatic charge patterns are formed for proliferating nerve cells in a circuit-like configuration. Japanese Unexamined Patent Public Disclosure No. 3-7576 attempts an arrangement of cultivated cells on a surface on which optically sensitive hydrophilic high polymers, which includes high polymers to which cells can attach and high polymers to which cells cannot attach, are patterned by a photolithography process. Japanese Unexamined Patent Public Disclosure No. 3-7577 suggests the use of functional groups to which cells can attach, formed by radiating ultraviolet rays and/or radioactive rays to cell incubating material having a surface to which cells cannot attach, and also suggests the use of polymerization initiator species formed by radiating ultraviolet rays and/or radioactive rays to cell incubating material. On the functional groups or the polymerization initiator species are polymerized monomer, which includes monomer to which cells can attach and monomer to which cells cannot attach, to form patterns on a surface to thereby control arranging cells.
Japanese Unexamined Patent Public Disclosure No. 5-176753 discloses the use of a cell incubating substrate on which is patterned a material such as collagen influencing cell shape and degree of cell attachment, and also discloses a method for fabricating such a substrate by means a photolithography process. By incubating cells on such a substrate, it is possible to attach cells to an area on which collagen is patterned to thereby accomplish patterning of cells.
In conventional methods for arranging cultivated cells in a desired pattern, a culture container containing therein cells and culture medium is allowed to stand when cells are incubated, similar to conventional methods for cultivating cells. However, in conventional methods in which a culture container is allowed to stand while incubating cells, when cells stay on an area which is processed so that cells should not attach thereto, the cells secrete extracellular matrix and thus may undesirably attach to the area anyway. As a result, cells can attach to an area on which cells are not desired, and to thereby pose a problem that a resolution of cell arrangement is deteriorated.